Cylinder Dryer Research Articles

A novel drying process for knitted fabrics based on heat-wet coupling model

The characteristics of high elasticity and easy deformation of knitted fabrics present challenges for traditional continuous flat drying processes. Shrinkage, uneven drying and dye migration are common problems with these processes. To address those problem, a novel dual-heat-supply drying process for knitted fabrics is proposed, which combines the characteristics of hot air drying and cylinder drying. By establishing a mechanical model of the fabric microelement, the force conditions of the fabric during the drying process are analyzed to prevent the occurrence of shrinkage. Consider the structural attributes of knitted fabrics and the diverse forms of water, a foundational unit model for single-sided weft knitted fabrics is proposed. The effective thermal conductivity of wet knitted fabrics in three directions is calculated through numerical simulation, and the validity of this method is preliminarily verified by comparison with literature experiments. The thermal-humidity coupling model is utilized to develop finite element models of cylinder drying and dual-heat-supply drying, which are then employed to conduct a comparative analysis of the two drying processes. The accuracy of the simulation results is verified through experiments, with the maximum deviation being less than 3.3 %. The results demonstrate that in comparison to cylinder drying, the temperature differential between the upper and lower surfaces of the fabric(ΔT) in dual-heat-supply drying is diminished by approximately 5 K. Additionally, the critical saturation point is reached approximately 10 s earlier, which effectively reduces the proclivity of dye migration and enhances the efficiency of the drying process. Finally, three process parameters (v, Tout and Th) is optimized for the dual-heat-supply drying process, 63.68 % reduction in ΔT, thereby further enhancing the quality of the drying process. The dual-heat-supply drying process represents an effective and significant improvement in the quality of knitted fabrics.

A novel spatio-temporal attention-based bidirectional LSTM model for moisture content prediction in drying process

Accurate prediction of moisture content is significantly crucial for ensuring process stability and product quality in the cylinder drying process. However, the drying process exhibits complex spatio-temporal characteristics and strong interference, which make accurate prediction challenging for the deep learning approach. To address this issue, this article proposes a new spatio-temporal attention-based bidirectional long-short temporal memory network (STA-BiLSTM) model for accurate moisture content prediction. First, Maximum Relevance Minimum Redundancy (mRMR) is adopted to identify optimal features highly related to moisture content. Secondly, bidirectional long-short temporal memory (Bi-LSTM) network is utilized to extract temporal dependencies from the sequential data. Subsequently, spatio-temporal attention mechanisms are designed to adaptively focus on the most relevant features and timesteps, enhancing the model’s generalization ability. Finally, due to the harsh industrial environment, eXtreme Gradient Boosting (XGBoost) is adapted to improve generalizability and robustness. Extensive experiments on a real industrial dataset of the drying process demonstrate that the proposed STA-BiLSTM approach significantly outperforms alternative approaches for predicting moisture content, validating its effectiveness and superiority.

Thermal Study of the Utilization of Rice Husks Using the Forced Convection Method as Energy for a Rotating Cylinder Dryer

Small farmers in rural areas use the sun as their main energy source to dry post-harvest products. Due to limited knowledge and technology, farmers depend on the sun through direct drying. Direct use of the sun for the drying process has disadvantages in uncertain weather such as cloudy or rainy. This results in the drying process not being optimal or even stopping. This research aims to use rice husks as energy to replace direct sun drying to produce optimal temperatures so that drying time is shorter and the quality of the dried food is hygienic. Rice husk as an energy source is applied through a rotating cylinder dryer. This dryer is tailored to farmers' needs, namely easy to operate at an affordable price. This energy can be utilized sustainably because it is abundant through a forced convection system and energy conversion using a heat exchanger. The design of the compact rotary dryer includes an integrated drying chamber in one unit with the combustion furnace and a heat exchanger. The drying chamber includes a rotating cylinder and a fixed cylinder. The test results show that hot air from burning rice husks flows through the heat exchange pipes by conduction from the furnace to the walls of the drying chamber and by forced convection through an exhaust fan installed in the drying chamber. The average environmental temperature of 29.55-29.69oC has increased when using one exhaust fan to 64.46oC and two exhaust fans to 60.11oC. This drying temperature can produce shorter drying times, so it can be applied to post-harvest product drying, which is energy-efficient and sustainable for small farmers. Based on research results, rotating cylinder dryers powered by rice husks are very suitable for small farmers to replace direct sun drying.

Experimental study and prediction of two-phase flow pattern distribution diagrams in multi-channel cylinder dryer

The multi-channel cylinder dryer (MCD) is designed to improve heat transfer. Although there are numerous research studies on the pressure drop, heat transfer characteristics, and flow pattern in static state of MCD, there is little research on the flow pattern in the rotating state. In this paper, the distribution of flow pattern in MCD under different rotating speeds and steam mass flow rates is studied. Furthermore, the logistic regression method (LR) is used to predict the flow pattern diagrams. The results show that in the front section of the flow channel, the flow pattern is basically annular flow, which is not affected by mass flow rate and rotating speed. On the other hand, wavy flow, vortex flow, slug flow, and bubble flow can be observed when the fluid enters the middle and the end section. The higher the rotating speed and the steam mass flow rate, the more the flow pattern tends to be an annular and wavy flow. At the end of the passage, the flow pattern is mainly slug flow. The predicted flow pattern diagrams are in good agreement with the experimental result, and to obtain an effective flow pattern in the middle and the end section of the flow channel, the influence of increasing rotating speed is greater than that of increasing steam mass flow rate. However, the specific rotating speed, steam mass flow rate, and other parameters should still be set by combining with the actual situation. This work can provide some references for the further study of MCD flow characteristics.

Experimental study on condensate heat transfer coefficient of multi-channel cylinder dryer integrated with Bayesian-optimized machine learning prediction

The condensation heat transfer coefficient of the multi-channel dryer, one of the key component of paper-making machine, directly determines the efficiency of heat energy utilization. However, the prediction of condensation heat transfer coefficient remains a challenge because the heat transfer characteristics in multi-channel dryer is a complex fundamental issue involving the thermal behavior of two-phase fluid systems. Herein, we successfully developed the four supervised machine learning models to predict the heat transfer coefficient of a multi-channel cylinder dryer under different working conditions. The multi-channel cylinder dryer experiments under different steam mass flux and cooling water mass flow rates were performed and the measured data is used as the input data for training. Interestingly, the four trained Bayesian-optimized machine models present the excellent capability of prediction for condensation heat transfer coefficient of multi-channel cylinder dryer, where the values of R 2 for tested Bayesian-optimized-based SVR, ANN, linear SVR, and RF are 0.983, 0.997, 0.996, and 0.953, respectively. In addition, the feature importance of descriptors is quantified based on a random forest algorithm. Our study suggests that machine learning models can effectively predict the condensate heat transfer coefficient of two-phase fluid systems, which not only would be beneficial to optimizing the structures and operation parameters of multi-channel cylinder dryer in the industry but to develop a reasonable correlation of heat transfer coefficient in fundamental research.

Possibilities of Reducing the Heat Energy Consumption in a Tissue Paper Machine—Case Study

The article presents studies on the impact of the significant process parameters of a paper machine with a Yankee cylinder on its production capacity and heat energy consumption for drying the paper web. Parameters such as machine speed, web moisture content before and after pressing, parameters of steam supplied to the cylinder and parameters of hot air flowing from the nozzles of the hood were analyzed. The study’s results were used to optimize production to improve the energy efficiency and performance of the machine. In order to use the possible methods of improving the production capacity and heat energy consumption, the parameters of the production process were measured and the basic indicators characterizing the operation of the machine were calculated in the Yankee cylinder–dryer hood system. The correct functioning of the machine components and the possibility of their modernization were also analyzed. Technological and construction changes introduced based on the research results made it possible to increase the production capacity by 10% and to reduce the consumption of heat energy per 1 ton of produced paper by 16.3%. The article presents a description of changes in the technology of paper production and modernization of the tissue machine made in the years 2013–2022.

Analysis of Cylinder Drying Intensity of Cut Tobacco Based on Enthalpy Method

Cylinder drying of cut tobacco is one of the key processing technologies in cigarette manufacturing. And complex mass transfer and heat transfer phenomena were involved. In this paper, a thermodynamic model have been built for cut tobacco during cylinder drying process. The relationship of different process parameters and thermodynamic data were analyzed by canonical correlation method, including amount of heat Qv produced in moisture evaporation of cut tobacco, amount of heat Qs produced in temperature increase of cut tobacco, total amount of heat Q and thermal efficiency coefficient η. The results showed that the thermodynamic model explained the actual cut tobacco heating and heat distribution well in the cylinder drying process. The variation coefficients of the four thermodynamic parameters of cut tobacco under the same processing conditions were all less than 5.0%. It is proved that the thermodynamic model established during cylinder drying process of cut tobacco is feasible.

Parametric Analysis of Cylinder Drying Process in Association with Various Materials

In this study, the heat and mass transfers in the fabric drying process of a single-cylinder dryer are numerically examined in detail by using MATLAB codes and illustrating 3D velocity and temperature profiles obtained by a CFD-ACE+ software package. Seven different drying materials including Polyethylene terephthalate (PET), Polyethylene, Polypropylene, Cotton, Wool, Rayon, and Nylon are employed as drying materials. Influences of the drying-material thickness, contacting percentage, cylinder temperature, feeding velocity, and cylinder diameter are examined in detail. For all cases in this study, it is found that the maximum temperature of the drying material in the drying process is strongly dependent on the thermal diffusivity of the drying material. The higher the thermal diffusivity of the drying material, the greater the peak temperature achieved. The peak temperature of the drying material increases with the increase in the contacting percentage. The higher feeding velocity leads to a faster increase in the temperature of the drying material; however, the peak temperature of the slower feeding velocity is higher than that of the faster one. The heat transfer between the central layer of the drying material and to ambient environment is limited by the thermal diffusivity of the drying material.

Experimental study on condensation heat transfer characteristics of steam in rectangular channels rotating about a parallel axis

• Nu in rotating channel increases with Re but decreases with steam temperature. • Pressure drop in rotating channel increases with Re and steam temperature. • Propose a new heat transfer correlation for steam condensation in rotating channel. In the papermaking industry, a kind of new cylinder dryer with multiple small and rectangular channels are employed to enhance the drying efficiency of drying machine. In practical working conditions, the multi-channel cylinder dryer runs under rotating states that could affect the heat transfer characteristics of the inside two-phase flow. However, the fluid heat transfer characteristics in the multi-channel at rotating states have not been well explored. In this study, a set of rotating experimental system is established to investigate the condensation characteristics and pressure drop changes of steam in rotating rectangular channels. Firstly, the experimental apparatus and the data processing method are described in detail. Then the effects of rotation speed, mass flux and steam temperature on the heat transfer coefficients and pressure drop are studied through experiment. The results show that when Re is small, the heat transfer coefficient first increases and then decreases with the increased Re ω ; when Re is large, the heat transfer coefficient increases with the increased Re ω . Moreover, the heat transfer coefficient decreases as the steam temperature increases. In addition, the pressure drop decreases with the increased Re ω while increases with the increased Re and steam temperature. Finally, a heat transfer model of two-phase flow condensation under rotating states is developed to predict the heat transfer coefficient of steam in rotating multiple channels.

Cut orientation effect on mass transfer: Drying and rehydration of yellow sweet potato cylinders

This work aimed to evaluate how cut orientation affects mass transfer during the drying and rehydration process. Sweet potato cylinders of 1.90 cm of diameter and 0.50 cm of height were prepared. Three cut orientations were carried out regarding the vascular tissue orientation, preparing longitudinal, transverse and oblique (45°) cuts. In addition, osmotic pretreatment (50°Brix sucrose solution) was also evaluated. Convective drying and rehydration kinetics were evaluated at a constant temperature. As results, cut orientation and osmotic pretreatment did not affect the drying kinetics. However, transverse cut without osmotic pretreatment presented less shrinkage than the other cut orientations. On the other hand, rehydration process was affected by cut orientation, being longitudinal cut the slowest sample absorbing water. In conclusion, both the cut orientation and osmotic dehydration did not show important effects on convective drying. Despite that, cut orientation affected shrinkage and rehydration kinetics of sweet potato cylinders.

Experimental study on condensation friction pressure drop in rotating channels and proposal of new correlation

The multi-channel cylinder dryer uses the small channels with high heat transfer efficiency to improve the drying efficiency. In practical working conditions, the multi-channel cylinder dryer runs under the rotating state, which would greatly affect the pressure drop of inside two-phase steam. However, the condensation friction pressure drop of two-phase flow in rotating channels has not been well explored. Herein, the condensation pressure drop of two-phase steam in rotating rectangular channels are elaborately studied based on a homemade rotating experiment system. The results show that the friction pressure drop of two-phase flow decreases with the increase of rotation Reynolds number, while increases with the increase of mass flux. Finally, a new correlation of friction pressure drop for two-phase flow condensation in rotating channels is proposed and evaluated by the experimental data.

Characterization of the Pressure Drop during Condensation in Channels of Multi-Channel Cylinder Dryer Using Homogeneous and Separated Flow Models

The condensation resistance characteristics of steam flow in horizontal rectangular channels of multi-channel cylinder dryer (MCD) is a very important factor that affects the heat transfer, while it is not very clear due to the limited studies. In this paper, the frictional resistance characteristics of the two-phase flow (steam and water) in the rectangular small channels of MCD were investigated with deionized water as the working fluid, and the calculation models, homogeneous and separated flow models, of the two-phase flow pressure drop in the channel were verified and evaluated. It showed that the main part of the total pressure drop was the frictional pressure drop, which means that the calculation of frictional pressure drop was the key to the calculation of the pressure drop of the two-phase flow in the channel. Meanwhile, it was found that the homogeneous model was not suitable for the calculation of the frictional pressure drop and the separated flow model was completely in line with the experimental data. In this study, the converted coefficient of complete steam/liquid phase were concerned to calculate the frictional resistance using five separated flow models. It was found that the Chisholm B model showed better accuracy than prior correlations, which was greatly consistent with experimental data, and the average absolute percentage deviation (MAPE) was 24.9%.

Development, validation, and comparison of FE modeling and ANN model for mixed-mode solar drying of potato cylinders.

This work aims to develop a finite element (FE) model for predicting temperature and moisture ratio of potato cylinders having diameters of 8, 10, 13mm and 50mm length during solar drying using COMSOL Multiphysics software. The developed model computed conduction, convection, and radiation with appropriate governing and boundary conditions by coupling heat transfer in solid, laminar flow, transport of diluted species, and moving mesh modules together. Moving mesh module was employed to embrace the effect of inevitable shrinkage parameter all through solar drying. Experimentations and calculations were done based on the requirement of FE model. The developed model showed the increment of product temperature from 299.51-313.73 K, 299.07-313.03 K, and 298.34-314.57 K in case of 8, 10, and 13mm diameter samples for an effective drying period of 3 h 15 min, 4 h 15 min, and 5 h, respectively. At the same time, the moisture content reduced from 83.57%, 86.57%, and 82.12% (wb) to 9.08%, 9.99%, 10.44% (wb) for the respective samples. To prove the reliability of the FE model predicted results, an attempt was made through the artificial neural network (ANN) model for describing the drying performance of the potato as well. It was found that the FE model better simulated the drying behavior with higher R2 values (R2 =0.988-0.995). The drying chamber air temperature was also simulated from FE model and validated with experimental data during drying of samples. The prediction capability of FE proposed model based on statistical error analysis showed lower values than ANN model. PRACTICAL APPLICATION: In the present study, the potential of mixed-mode solar drying in food processing industries was established showing detailed investigation of transport processes throughout the solar drying process of potato cylinders. The established finite element (FE) model can be considered as a realistic alternative to experimentation. The food processing industries and dryer engineers can achieve better quality dried products by precisely operating the dryers at the optimum condition by help of the proposed FE model and product shrinkage analysis.

Research on Flow and Condensation Heat Transfer Coefficient of multi-channel cylinder dryer in U-shaped Section

The cylinder dryer is the most energy-consuming part of the papermaking drying section. Whether the drying cylinder can effectively drain the drying cylinder affects the drying efficiency of the drying cylinder. The design of the multi-channel drying cylinder effectively improves the problem of the difficulty of the water accumulation discharge. In order to obtain a channel cross-sectional shape with better drainage and better heat transfer, two channels with different cross-sectional shapes are selected to study the flow and heat transfer of steam in this experiment. The changes of the channel heat transfer coefficient under different working conditions are studied and compared. The result show that the U-shaped channel heat transfer effect is better than that of other shape channels in the multi-channel dryer.

Heat Transfer Characteristics in Horizontal Rectangular Channel of Multi-Channel Cylinder Dryer

Heat Transfer Characteristics in Horizontal Rectangular Channel of Multi-Channel Cylinder Dryer

Experimental study on municipal sludge rotary deep dewatering device

In view of the problem of drying high-humidity and high-viscosity sludge, it is analyzed in the water characteristics and drying characteristics of municipal sludge, optimizing the design of key components of ordinary rotary cylinder dryer and conducting industrial simulation experiments. The results show that: the self-cleaning and dispersing rotary cylinder dryer has higher heat exchange efficiency, smaller discharge particles and better drying effect than ordinary rotary cylinder dryer, which is a useful exploration for the research, development and popularization of municipal sludge deep dewatering process.

Intensification of Paper Drying on Drying Cylinders

One of the most energy-intensive processes is the drying process. Therefore, an important task is to reduce heat consumption for drying. Various ways to improve the drying devices of paper and cardboard machines are identified. The main disadvantages of these improvements are given. The limiting factor of heat transfer from water vapor to paper is established. The dependence of thermal resistance on the thickness of the condensate layer is given. The authors have developed a new design for condensate drainage. The developed design allows installing movable siphons without replacement of steam inlet heads of the old type (for fixed siphons) with their insignificant modernization and cutting of an annular groove inside the drying cylinder. This will ensure a minimum level of condensate and eliminate the possibility of suction of steam into the condensate return system. Additionally, this will reduce thermal resistance, heat loss, and reduce energy consumption for paper drying as a whole. Keywords: paper drying, moisture content, drying cylinder, thermal resistance, heat transfer.

PENERAPAN MESIN PENGERING JAGUNG UNTUK PETANI TEBUWUNG

Extend the shelf life of food products so that they can be consumed longer. Corn is an important food commodity in Tebuwung Village, Dukun District, Gresik Regency because it is a food other than rice. To extend the shelf life of corn, it is necessary to go through a drying process. One of the drying equipment that can be used is rotary rotating type dryer (rotary dryer). The heat source of the dryer can come from corn stalks to reduce the scent as a source of burning heat. The problem is there is no available drying equipment suitable for corn drying in Tebuwung Village, Dukun District, Gresik Regency. For this reason, a study was conducted to design a rotary type drying machine for heat-sourced corn originating from the burning of corn cobs. This study aims to produce a rotary type corn drying machine with a source of burning corn cobs. The test parameter is the rotating drying cylinder which affects the drying time of corn in the drying chamber. Through this research, a rotary type drying machine has been produced for drying corn in Tebuwung Village, Dukun District, Gresik Regency. The test results with a rotating cylinder speed ratio of 1400 rpm and 280 rpm are 42 minutes long drying and require power of 522.85 watts with electricity costs of Rp. 500.24 for 900 VA and Rp. 542,936 for 1,300 VA power

Kajian Eksperimental Penggunaan Ruang Pengering Silinder Vertikal dan Horisontal Mesin Pengering Gabah Tipe Fluidzed Deep

Abstract— This study explored experimentally the use of vertical and horisontal position of cylindrical drying chamber dryer Fluidzed Deep against temperature distribution, humidity, drying rate, decreasing grain water level, and decreasing grain mass. The method used in this research is design and experiment. This machine uses a burning furnace as a heat source,sengon/ albasia wood as fuel, flat plate type heat exchanger, cyclone to convert wet vapor to dry vapor, filter to dry vapor cleaner, cylindrical drying chamber, blower to blow air, and Jig to support all components. This experiment was carried out three times for the drying chamber in a vertical position, and three times for the drying chamber in a horisontal position. In one drying time, it takes about 270 minutes. In the drying chamber measured temperature and humidity at 12 points of measurement. The results showed that the horisontal cylinder drying chamber produced higher temperature distribution than the vertical cylinder drying chamber, but the temperature distribution was less even, the vertical cylinder dryer produced lower humidity than the horisontal cylinder drying chamber, but resulted in higher deviation than the horisontal cylinder dryer. Drying rate, decrease in grain water content, average grain decrease on average faster than horisontal cylinder. The process of reducing the grain moisture content from about 20% bb to a moisture content of dry milled grains of about 14% bb occurred for 270 minutes or about 4, 5 hours. Keyword: Experimental design; Fluized deep dryer; dryer efficiency

Heat transfer analysis during mixed-mode solar drying of potato cylinders incorporating shrinkage: Numerical simulation and experimental validation

Heat transfer analysis during mixed-mode solar drying of foodstuff is crucial in food industries now-a-days as better understanding of the phenomena will assist in suitable design and optimization of the drying process parameters. In the present work, natural convection mixed-mode solar drying experiments were carried out with potato cylinders of varying diameters (8, 10 and 13mm) with a fixed length of 50mm. The convective heat transfer coefficient, hcon was evaluated without and with the incorporation of shrinkage effect in the mathematical model. The results predicted that consideration of sample shrinkage led to an overestimation of average values of convective heat transfer coefficient, h¯con by 55.72–61.86% for the investigated samples. It was also observed that the moisture content and sample diameter had a notable influence on heat transfer coefficient. Heat transfer correlations in terms of dimensionless numbers were developed for each sample diameter by an equation of the form Nu=C(Ra)n. The uncertainty in the average value of hcon was found to lie in the range of 1–3%. A finite element based COMSOL Multiphysics software was used to develop a numerical model to project the transient sample temperature during the drying process. The predicted sample temperatures considering shrinkage were in close agreement with the experimental results showing lower values of statistical errors.